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| author | Reilly Grant <reillyg@chromium.org> | 2016-02-21 18:38:01 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-03-05 12:05:01 -0800 |
| commit | d883f52e1f6d2eca8378e3795f333c1396943873 (patch) | |
| tree | 849a84ea953f7adf6869229156f1b6bd97a77f4b /Documentation/DocBook | |
| parent | 3d0712deb0a416021e55febc7ec7f6c24f460e06 (diff) | |
| download | linux-d883f52e1f6d2eca8378e3795f333c1396943873.tar.bz2 | |
usb: devio: Add ioctl to disallow detaching kernel USB drivers.
The new USBDEVFS_DROP_PRIVILEGES ioctl allows a process to voluntarily
relinquish the ability to issue other ioctls that may interfere with
other processes and drivers that have claimed an interface on the
device.
This commit also includes a simple utility to be able to test the
ioctl, located at Documentation/usb/usbdevfs-drop-permissions.c
Example (with qemu-kvm's input device):
$ lsusb
...
Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd
$ usb-devices
...
C: #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=02 Driver=usbhid
$ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
OK: privileges dropped!
Available options:
[0] Exit now
[1] Reset device. Should fail if device is in use
[2] Claim 4 interfaces. Should succeed where not in use
[3] Narrow interface permission mask
Which option shall I run?: 1
ERROR: USBDEVFS_RESET failed! (1 - Operation not permitted)
Which test shall I run next?: 2
ERROR claiming if 0 (1 - Operation not permitted)
ERROR claiming if 1 (1 - Operation not permitted)
ERROR claiming if 2 (1 - Operation not permitted)
ERROR claiming if 3 (1 - Operation not permitted)
Which test shall I run next?: 0
After unbinding usbhid:
$ usb-devices
...
I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=02 Driver=(none)
$ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
...
Which option shall I run?: 2
OK: claimed if 0
ERROR claiming if 1 (1 - Operation not permitted)
ERROR claiming if 2 (1 - Operation not permitted)
ERROR claiming if 3 (1 - Operation not permitted)
Which test shall I run next?: 1
OK: USBDEVFS_RESET succeeded
Which test shall I run next?: 0
After unbinding usbhid and restricting the mask:
$ sudo ./usbdevfs-drop-permissions /dev/bus/usb/001/002
...
Which option shall I run?: 3
Insert new mask: 0
OK: privileges dropped!
Which test shall I run next?: 2
ERROR claiming if 0 (1 - Operation not permitted)
ERROR claiming if 1 (1 - Operation not permitted)
ERROR claiming if 2 (1 - Operation not permitted)
ERROR claiming if 3 (1 - Operation not permitted)
Signed-off-by: Reilly Grant <reillyg@chromium.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/DocBook')
| -rw-r--r-- | Documentation/DocBook/usb.tmpl | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/DocBook/usb.tmpl b/Documentation/DocBook/usb.tmpl index 4cd5b2cd0f3d..bc776be0f19c 100644 --- a/Documentation/DocBook/usb.tmpl +++ b/Documentation/DocBook/usb.tmpl @@ -732,6 +732,18 @@ usbdev_ioctl (int fd, int ifno, unsigned request, void *param) or SET_INTERFACE. </para></warning></listitem></varlistentry> + <varlistentry><term>USBDEVFS_DROP_PRIVILEGES</term> + <listitem><para>This is used to relinquish the ability + to do certain operations which are considered to be + privileged on a usbfs file descriptor. + This includes claiming arbitrary interfaces, resetting + a device on which there are currently claimed interfaces + from other users, and issuing USBDEVFS_IOCTL calls. + The ioctl parameter is a 32 bit mask of interfaces + the user is allowed to claim on this file descriptor. + You may issue this ioctl more than one time to narrow + said mask. + </para></listitem></varlistentry> </variablelist> </sect2> |